Internal combustion engine with rotary piston

ABSTRACT

This invention relates to an internal combustion engine with rotary piston, whereby in a stator with the inside space limited by an oval skirt area a rotary piston of triangular shape, guided by plane parallel side areas of the stator, is moved such that the gravity center of the rotary piston executes a translation along a closed course and that its angle parts slide along the inner skirt area of the stator, forming thereby three closed volume-variable generating spaces.

)[11] 3,799,705 Mar. 26, 1974 INTERNAL COMBUSTION ENGINE WITI-I ROTARY PISTON Ernst Mac Gunthard, l-laldenstr. 127, Zurich, Switzerland Filed: Oct. 3, 1972 Appl. N0.: 294,639

Inventor:

Foreign Application Priority Data Aug. 19, 1972 Switzerland 12260/72 US. Cl. 418/61 A, 123/845 Int. Cl. F01c l/02, F04c 1/02, F04c 17/02 Field of Search 418/61; 123/845 [56] References Cited UNITED STATES PATENTS 3,056,391 10/1962 I-Ioadley 418/57 3,205,872 9/1965 Pomasanow l23/8.45 3,253,580 5/1966 Eberhard eta]. 418/61 Primary Examiner-Carltori R. Croyle Assistant ExaminerJohn J. Vrablik 5 7] ABSTRACT This invention relates to an internal combustion engine with rotary piston, whereby in a stator with the inside space limited by an oval skirt area a rotary piston of triangular shape, guided by plane parallel side areas of the stator, is moved such that the gravity center of the rotarypiston executes a translation along a closed course and that its angle parts slide along the inner skirt area of the stator, forming thereby three closed volume-variable generating spaces.

7 Claims, 10 Drawing Figures INTERNAL COMBUSTION ENGINE WITH ROTARY PISTON BRIEF SUMMARY OF THE INVENTION In known internal combustion engines with rotary piston of this kind, the gravity center of the rotary piston defines a circular path around a drive shaft which is centrally supported in the stator. The rotary piston is connected with the stator by a gearing which fixes the rotating motion of the rotary piston regarding rotating position and sense of rotation in dependence of the circular path motion of the gravity center of the piston. The engines constructed on this kinematical basic have fundamental disadvantages in mechanical and thermodynamical respect, which it has been possible to only partially resolve.

The object of the invention is. to create an internal combustion engine with rotary piston of the above mentioned kind which on strength of another kinematic concept allows better mechanical and thermodynamic solutions. i

The internal combustion engine with rotary piston according to the invention is characterized by the fact that the rotary piston in successive rotary phases with the same sense of rotation is tilting alternatingly about one of two centers of rotation lying at the axis-nearest 'zone of the inside skirt area of the stator, and this successively about one of its angle parts, so that the rotary piston shuttles to and fro between two end positions, describing thereby with its gravity center an elliptic path.

BRIEF DESCRIPTION OF THE DRAWING FIG. 3 a cross-section along the line III-III of FIG. 1; I

FIG. 4 a'representation of the geometric relationships of the rotary piston and the interior skirt area of the stator;

FIGS. to a schematic representation of 18 operation phases of the engine.

DETAILED DESCRIPTION OF THE DRAWING The represented internal combustion engine with rotary piston has a stator 1, of which the interior space is limited. by an oval skirt area '2 and plane parallel side areas 3 and 4. The stator 1 consists of two parts la and 1b, of which the part It: forms the skirt area 2 and the side area 3, and the part lb the other side area 4 of the inner space.

In the stator I is a centrally supported drive shaft 5 which is subdivided in two parts 5a and 5b, whereby the drive shaft parts 5a and 5b extend from outside with their opposite ends up to the side areas 3 and 4, respectively, into the stator l.

The inner space of the stator 1 contains a triangular shaped rotary piston 6, guided axially by the plane parallel side areas 3 and 4 of the stator, which piston is rotating on its gravity center upon a piston pin 7. The piston pin 7 is disposed between the opposite ends of the drive shaft parts 5a and 5b and connected with them by the eccentric 8. This eccentric consists of the two coaxial eccentric pivots 8a and 8b which prop one another at the point 9, and of which the one eccentric pivot 8a is fixedly connected with the drive shaft part 5a, and the other eccentric pivot 8b with the drive shaft part 5b. The piston pin 7 is free to rotate on the eccentric pivot 8a. The eccentric axis 10 is eccentric both to the piston shaft axis 11 and to the drive shaft axis 12.

An auxiliary gearing (FIGS. 1 and 3) is provided in order to fix the sense of rotatibn of the rotary piston 6 by starting the drive shaft 5a, 5b, which auxiliary gearing moves the rotary piston relative to the stator l in the opposite sense. of rotation to that of the drive shaft.

The auxiliary gearing is disposed at one side of the rotary piston 6 and consists of an internally toothed gear rim 13, which is disposed coaxially to the piston shaft axis 11 and connected fixedly with the rotary piston,

and of four gears with external toothing 14, 15, 16 and 17, of which ,the one essential for the function of the auxiliary gearing, the toothed gear 14 meshing with the gear rim 13, is disposed coaxially to the eccentric axis 10 and connected fixedly with the drive shaft part 5b. The remaining toothed gears are freely rotatably supported in the piston shaft 7. The radius of the gear rim 13 is three times as large as that of the mutually equalsized toothed gears 14, 15, 16 and 17, and corresponds to the ratio 1 3 of the number of revolutions of the rotary piston 6 to the number of revolutions of the drive shaft.

At theturned away side with regard to the auxiliary gearing the rotary piston has a guide (FIGS. 1 and 2) which causes during the motion of the .rotary piston 6 the gravity center of the latter (the piston shaft axis 11) to describe an elliptic path, and which together with the auxiliary gearing determines the position of the rotary piston 6 with regard to the stator 1. This guide consists of a pilot 18 disposed on the piston shaft 7, which pilot slidesupon the alignment path 21 formed by the two jaws l9 and 20, whereby in order to reduce the friction the direct sliding contact is effected by a roller bearing 22 seated upon the pilot 18. The axis 23 of the pilot 18' lies in the line connecting the piston shaft axis 11 and the eccentric axis 10 and between these two axes, and is at a distance from the piston shaft 11 equal to the shortest distance (b in FIG. 4) from the gravity center of the rotary piston 6 to the drive shaft axis 12.

In the stator part la is provided a slit 24 for the inlet (E) of the combustible mixture, and a slit 25 for the outlet (A) of the combustion gases. The stator 1 possesses furthermore at its parts la and lb the openings 26 for the inlet and outlet of lubrication oil. Numeral 27 designates the spark plug.

At the corners of the rotary piston 6 are disposed three axis-parallel sealing ledges 28 which are supported radially movable in nuts 29 and which slide along the skirt areas of the stator inner space during the movement of the rotary piston 6. For lateral sealing of the rotary piston 6 against the side areas 3 and 4 of the inner space of the stator there are provided sealing ledges 30 on the rotary piston 6. Furthermore, the piston shaft 7 has through-bores 31 for the circulation of lubricating oil. On the other areas of skirt 32 of the retary piston 6 are provided three recesses 33 which are dimensioned according the desired compression ratio of the engine.

' As it appears from FIG. 4, the geometric structure of the inner skirt area 2 of the stator 1 and the outer skirt area 32 of the rotary piston 6 is based on congruent equilateral triangles. The stator inner space shows four space centers determined by the angles A, B, C and D of a rhombus formed by two equilateral triangles with leg length s; and the rotary piston 6 shows three body centers formed in the represented position by the angles A, B and D of an equilateral triangle with the leg length s, which body centers constitute the central points of circles of curvature with a radius r, of the arcs of circle m limiting the angle parts of the outer skirt area 32 of the rotary piston 6. The curvature radius r, may be selected at liberty. It is preferably about one third of the leg length a of the equilateral triangles. In the represented example, the arcs of circle m are connected together by flattopped arcs of circle n of a radius r whereby the radius r shall be greater than the total of leg length s and radius r,, and is chosen according the desired compression ratio of the engine. Owing to circumstances, the arcs of circle n may be replaced by the tangents t to the arcs of circle m (one tangent is indicated by a dot-dash line).

M designates the gravity center (piston shaft axis 11) of the rotary piston 6, with E the center of the eccentric 8 (eccentric axis 10), and with Z the center of the stator (drive shaft center 12). The largest distance a and the smallest distance b from the piston shaft axis 11 (M) to the drive shaft axis 12 (Z), and the distance k from the eccentric axis 10 (E) to the piston shaft axis 11 (M), and the distance r from the eccentric axis 10 (E) to the drive shaft axis 12 (Z) are chosen such that the following equations are established:

On basis of these equations and of the presence of the pilot 18, 21 (FIGS. 1 to 3) the gravity center M of the rotary piston 6 describes, at a full revolution of the drive shaft about its axis 12 (Z), an elliptic path e, whereby a represents the large and b the small semiaxis of the elliptic path 2, the center of which lies in the drive shaft axis 12 (Z).

A rotation of the rotary piston 6 around the piston shaft axis 11 (M), emanating from the drive shaft 5 and forced by the auxiliary gearing 13, 14 and the pilot 18, 21, causes the rotary piston 6, in successive rotary phases in the same sense of rotation, to tilt alternately around one of the two space centers B, D of the stator inner space so that the rotary piston-6 shuttles to and fro between the two end positions. In both tilting end positions of the rotary piston 6 the triangle (ABD) determining the body centers of the rotary piston coincides each time with one of the two triangles ABD and BCD determining the space centers of the stator inner space. The stator inner space corresponds to the space required by the movement of the rotary piston 6, i.e., the envelope curve h of all possible positions of the moving rotary piston 6 represents the inner skirt area 2 of the stator 1. In practice, the inner skirt area takes a natural course which may be somewhat outside the envelope curve h, because of the necessary tolerance setting.

Strictly speaking, the respective tilting center does not stay, during the proceeding from the one to the other end position of tilting of the rotary piston 6, at the same point of the relating space center B or D, but

moves upon a small shallow loop about this space center.

Supposing the drive shaft 5 turns in direction of the arrow 34 (FIGS. 2 and 3), then the gravity center M (piston shaft axis 11) of the rotary piston 6 moves in the opposite direction about the stator center Z (drive shaft axis 12), and the rotary piston 6 turns with regard to the stator 1 also in opposite direction of rotation (arrow 35 in FIGS. 2 and 3) to that of the drive shaft 5. Regarding the piston shaft 11 the sense of rotation of the rotary piston 6 is reverse.

Between the outer skirt area 32 of the rotary piston 6 and the inner skirt area 2 of the stator 1 are formed three sealed generating spaces by the corners of the rotary piston 6 sliding along the inner skirt area 2, whereby the volumes of the generating spaces vary,

I with the movement of the rotary piston 6, between a minimum and a maximum.

During a full rotation of the rotary piston 6 with regard to the stator 1 the rotary piston 6 shuttles six times from the one to the other tilting end position. The volume of each of the three generating spaces changes thereby four times between the two extreme values so that the engine may be operated in a four-stroke cycle. The drive shaft 5 executes thereby three revolutions. Since with one revolution of the rotary piston a full working cycle of four strokes takes place in a generating space, and since in all three generating spaces there occur at the same time working cycles with shifted phases, a working cycle results with each revolution of the drive shaft.

In FIGS. 5 to 10 are represented six successive positions of the rotary piston 6, whereby the rotary piston turns counterclockwise. With the help of these figures the separate working phases in the three generating spaces U, V and W are described as follows:

FIG. 5 shows the rotary piston 6 in the tilting end position at left. In the generating space U begins just the suction of the gas-air mixture through the intake E. The suction is finished when the rotary piston 6 has reached the tilting end position at right (FIG. 8). FIG. 9 and 10 show the compression phase in the generating space U, which is practically finished when the rotary piston 6 has reached again the tilting end position at left. In FIG. 5 this state is shown as the generating space V. From this position of the rotary piston 6 until it reaches its tilting end position at right (FIG. 8) the generating space V, and thus the gas-air mixture in state of compression, is practically displaced without modification of volume, whereby a violent vorticity of the gas-air mixture takes place (alluded to in FIG. 6). In the intermediate position of the rotary piston 6 as per FIG. 7 the ignition of the gas-air mixture takes place in the generating space V. As soon as the rotary piston 6 reaches the tilting end position at right according to FIG. 8, the combustion is practically terminated, thus before the expansion begins. FIGS. 9 and 10 show the expansion phase in the generating space V. The pressure generated by the consumed gases produces at the gravity center of the rotary piston 6 the strength which through the eccentric 8 gives the necessary torque to the drive shaft 5. Towards the end of the expansion phase (FIG. 10) begins the exhaust of the combustion gases from the generating space V through the outlet A. The continuation of the exhaust phase is shown in FIG. 5 to 8 for the generating space W. During the motion of the rotary piston 6 from the right to the left tilting end position (FIGS. 8 to 10) the generating space W is practically displaced without modification of the volume, whereby the remaining combustion gases are expelled almost completely relieved and the transition to the suction phase is initiated.

A complete working cycle is composed of six phases, during which the rotary piston 6 turns each time by 60 in the stator l, passing thereby from one tilting end position to the other, namely, through the suction phase (increase of volume), the compression phase (decrease of volume), the expansion phase (increase of volume), the exhaust phase (decrease of volume) and one phase each with practically constant working volume at the end of the compression phase and at the end of the exhaust phase. The four power strokes of the engine are therefore of various lengths, namely, the compression stroke and the exhaust stroke with a double duration compared to the suction stroke and the expansion stroke.

The lengthened compression stroke allows practically a total combustion of the fuel gases and produces consequently almost poisonfree and smogfree exhaust gases. Furthermore, the said circumstances achieve that the combustion process is closed before the expansion phase begins, so that in the described engine of this kind the expansion may ensue abiatically, whereby the working cycle comes closer to the ideal continuous process, which means a better thermal efficiency and therefore a higher specific output of the engine.

By reason of the chosen kinematical concepts, there can be obtained with the described engine much higher volume changes of the working spaces than with the known rotary piston engines where the gravity center of the rotary piston describes a circular path. The engine may be conceived either with high or extremely low compression so that Otto carburetor engines operated with natural gasoline or low octane gasoline as diesel engines may be constructed after the described principle.

In an engine which is destined to work after the diesel principle, there is disposed advantageously on each side of the rotary piston an alignment path of the said kind, and in the middle of the rotary piston, with bisection of the piston shaft, an auxiliary gearing. With such a construction theveccentric pivots on both sides can be formed stronger.

A further advantage of the described engine consists in that the piston gravity center and the drive shaft have mutually opposite directions of rotation. This circumstance means that the torque at the drive shaft and the moment of reaction (pitching moment) are unidirected, through which the suspension of the stator of the loaded engine is less stressed one-sidedly.

Several of the described engine units may of course be united in the known manner in order to obtain a multi-piston engine.

What is claimed is:

1 An internal combustion engine with rotary piston comprising:

a stator, the inner space of which defines a skirt of oval shape;

a triangular rotary piston which rotates about its center of gravity upon a piston shaft within said inner space, the corners of said piston being adapted to slide along the inner skirt area of said stator, thus forming three enclosed, volume-variable working spaces; an eccentric coupled to said piston shaft,

said piston shaft being free to rotate upon said eccentric;

a supported drive shaft whose axis extends through the center of said stator, said eccentric being supported in the relating shaft and freely rotatable on at least one side, the axis of said eccentric being offset from the axes of both said piston shaft and said drive shaft;

axial guide means for said piston defined by plane parallel side walls of said stator and guide jaws thereon, said guide means confining the motion of said center of gravity of the rotary piston to a translational motion along a closed path, wherein said rotary piston, during rotation in one direction alternately tilts about one of two centers of rotation lying adjacent the more broadly curved walls of the inner skirt area of the stator, the corners of said piston successively being positioned at each of the two centers so that the rotary piston shuttles to and fro between two end positions, and so that said center of gravity describes thereby an elliptical path.

2. An internal combustion engine with rotary piston according to claim 1, wherein the geometric construction of the inner skirt area of the stator and the inner skirt area of the rotary piston are based on congruent equilateral triangles, whereby the stator inner space defines four space centers fixed by the angles of a rhombus formed by two of such triangles, and the rotary piston defines three body centers fixed by the angles of such a triangle, which body centers form the center points of circles of curvature of arcs limiting the outer skirt area of the rotary piston at its corners; and wherein the triangle determining the body centers of the rotary piston coincides each time with tilting end positions of the rotary piston with a triangle determing the space centers of the stator inner space.

3. An internal combustion engine according to claim 2, wherein the larges distance, a, and the smallest distance, b, of the gravity center of the rotary piston from the axis of the drive shaft, and the distance, k, of the eccentric axis from the piston shaft axis, and the distance, r, of the eccentric axis from the drive shaft axis are selected such that the following relations will apply to:

axis of which lies in the plane formed by the piston.

shaft axis and the eccentric axis and between these two axes, and which has a distance from the piston shaft axis equal to the shortest distance of the gravity center of the rotary piston to the drive shaft axis.

6. An internal combustion engine according to claim 4, wherein the auxiliary gearing consists of a gear rim with inner toothing which is disposed coaxially with the piston shaft axis and is connected fixedly with the rotary piston, and with at least an externally toothed gear which is disposed coaxially with the eccentric axis and 8 shaft is disposed between the mutually opposite ends of the drive shaft parts and connected with them by an eccentric pivot. 

1. An internal combustion engine with rotary piston comprising: a stator, the inner space of which defines a skirt of oval shape; a triangular rotary piston which rotates about its center of gravity upon a piston shaft within said inner space, the corners of said piston being adapted to slide along the inner skirt area of said stator, thus forming three enclosed, volumevariable working spaces; an eccentric coupled to said piston shaft, said piston shaft being free to rotate upon said eccentric; a supported drive shaft whose axis extends through the center of said stator, said eccentric being supported in the relating shaft and freely rotatable on at least one side, the axis of said eccentric being offset from the axes of both said piston shaft and said drive shaft; axial guide means for said piston defined by plane parallel side walls of said stator and guide jaws thereon, said guide means confining the motion of said center of gravity of the rotary piston to a translational motion along a closed path, wherein said rotary piston, during rotation in one direction alternately tilts about one of two centers of rotation lying adjacent the more broadly curved walls of the inner skirt area of the stator, the corners of said piston successively being positioned at each of the two centers so that the rotary piston shuttles to and fro between two end positions, and so that said center of gravity describes thereby an elliptical path.
 2. An internal combustion engine with rotary piston according to claim 1, wherein the geometric construction of the inner skirt area of the stator and the inner skirt area of the rotary piston are based on congruent equilateral triangles, whereby the stator inner space defines four space centers fixed by the angles of a rhombus formed by two of such triangles, and the rotary piston defines three body centers fixed by the angles of such a triangle, which body centers form the center points of circles of curvature of arcs limiting the outer skirt area of the rotary piston at its corners; and wherein the triangle determining the body centers of the rotary piston coincides each time with tilting end positions of the rotAry piston with a triangle determing the space centers of the stator inner space.
 3. An internal combustion engine according to claim 2, wherein the larges distance, a, and the smallest distance, b, of the gravity center of the rotary piston from the axis of the drive shaft, and the distance, k, of the eccentric axis from the piston shaft axis, and the distance, r, of the eccentric axis from the drive shaft axis are selected such that the following relations will apply to: (a + b/2) k, (a - b/2) r and k2 r2 + b (k + r).
 4. An internal combustion engine according to claim 3, including: an auxiliary gearing which moves the rotary piston with reference to the stator in an opposite sense of rotation to that of the drive shaft, and a rotary piston guide which together with the auxiliary gearing determines the position of the rotary piston with reference to the stator.
 5. An internal combustion engine according to claim 2, wherein the piston shaft is provided with a pilot which glides between said guide jaws on said side walls of said stator in a fixedly disposed guide path, and the axis of which lies in the plane formed by the piston shaft axis and the eccentric axis and between these two axes, and which has a distance from the piston shaft axis equal to the shortest distance of the gravity center of the rotary piston to the drive shaft axis.
 6. An internal combustion engine according to claim 4, wherein the auxiliary gearing consists of a gear rim with inner toothing which is disposed coaxially with the piston shaft axis and is connected fixedly with the rotary piston, and with at least an externally toothed gear which is disposed coaxially with the eccentric axis and is connected fixedly with the drive shaft, whereby the radius of the gear rim is three times as large as that of the toothed gear.
 7. An internal combustion engine according to claim 6, wherein the drive shaft is subdivided, and the piston shaft is disposed between the mutually opposite ends of the drive shaft parts and connected with them by an eccentric pivot. 